Cinder Block (CMU) Offset Smoker

by jason_5hundy in Outside > Fire

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Cinder Block (CMU) Offset Smoker

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For a small fraction the price of a heavy steel smoker, you can setup a large capacity cinder block version. Not only will it be cheaper it will be better insulated. Follow the instructions attached for a very effective, efficient and not bad looking unit.

Design & Dimension

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Review design dimensions.

Clear Area

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  1. Clear appropriate sized area with offsets as needed.
  2. Soften and level dirt or ad layer of sand.

Procure Cinder Blocks & Bricks

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  • Cinder Block: 8x8x16 (Qty. 60)
  • Cinder Block (1/2): 8x8x8 (Qty. 15)
  • Cinder Block (Caps): 8x2x16 (Qty. 16)
  • Clay Brick: 4.5x9x1.75 (Qty. 24)

Base Layers

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  1. Place base layer of cinder blocks and use level to confirm flatness.
  2. Alternate seem on each level.
  3. Eliminate all air gaps.

Complete Firebox

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  1. Build firebox with rotated CMU bricks for air inlet and outlet as shown.

Complete Chimney Structure

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  1. With a chisel, break a 1/2 brick into half again so that the chimney has an opening as shown in picture.
  2. Stack chimney to 3 blocks high for appropriate air draw.

Add Top Caps

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  1. Place top caps on alternating seems from cinder blocks underneath. (Top caps will ad a flat surface for lids to seal better)

Lid Construction

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Lid Dimensions: 30.5" x 38" (Qty. 2)

  1. Cut plywood to dimensions.
  2. Procure Heat Shield Insulation (4 ft x 6 ft) and cut to same dimension as plywood.
  3. Using a staple gun, apply insulation to bottom side of wood.
  4. Fasten two lid pieces with hinges in middle and and handles.

Add Clay Bricks

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  1. Line the inner firebox with clay bricks for extra heat protection for the concrete blocks.

Rebar Grate Support

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  1. Measure off alignment for rebar supports. (3 places)
  2. Using a 1/2 inch concrete drill bit, drill holes through only one side of blocks.
  3. Insert 25" long, 3/8" rebar.
  4. Procure or cut, 3/4" X 13 ga. flattened expanded metal sheet to 22" x 53"
  5. Place expanded metal on top of rebar for a cook grate.

Fire Box Lid

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  1. Procure 29" x 31", 3/16" thick carbon steel plate.
  2. Drill and bolt in handles for easier removal (not shown)

3/16 steel plate is necessary for firebox as temperature here will be too extreme for thinner materials

How to Use

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Now you're ready to test it out!

  • Use a left over block as a damper for your incoming fire vent. Slide back and forth to adjust heat.
  • Leave stack vent open at all times.
  • Add another expanded metal grate over the fire-pit if you would like the option to grill over the fire. (Good for tri-tip and chicken)

(This specific pit has about a 20 degree difference from one side to the other....which is actually very impressive.)